This invention relates to fluid dispensing closures fabricated of plastic materials. The closures are designed for insert molding into plastic containers such as pails. The benefits offered by insert molding include tamper evident attachment, superior leak resistance and lower manufacturing costs.
Tamper evident closures can help prevent theft, dilution, exchange or contamination of valuable container contents. Closures attached with a permanent insert molded bond between closure and container lid are tamper evident as the bond once broken cannot easily be repaired. Closures commonly attached by the use of metal crimp rings or by plastic snap fit are not considered tamper evident. These closures may be removed and replaced with new closures without evidence of tampering. Closures attached by ultrasonic welding meet the tamper evident criteria, but ultrasonic welding is a slow and more technically difficult process.
For container leak resistance and mechanical drop strength, the insert molded closure must be securely attached to the lid polymer. Where the container lid polymer is not fully compatible with the closure polymer (such as polypropylene with polyethylene) this invention discloses the use of top and bottom circumferential recesses on the body skirt. During molding the lid polymer enters the skirt recesses and mechanically locks the closure to the lid.
Another objective of this new design is to lower container manufacturing costs. A cap bail smaller in diameter than the body clamp flange permits the lower cost pre-assembly of the closure cap to the closure body. The outer annular closure body skirt helps separate parts for orientation, feeding and insertion by automated parts handling equipment. While these closures may be placed in the mold manually, the improved closure design facilitates automated insert molding.